Fuel tank pressure regulator

ABSTRACT

A fuel tank vent valve includes a venting apparatus for regulating discharge of fuel vapor from a fuel tank and admission of outside air into a fuel tank. The vent valve is used to regulate pressure in a fuel tank.

PRIORITY CLAIM

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Application No. 62/145,068, filed Apr. 9, 2015, which isexpressly incorporated by reference herein.

BACKGROUND

The present disclosure relates to fuel tank vent valves, andparticularly to venting apparatus for regulating discharge of fuel vaporfrom a fuel tank and admission of outside air into the fuel tank. Moreparticularly, the present disclosure relates to a fuel tank pressureregulator including a solenoid-activated fuel tank vent valve.

Vehicle fuel systems include valves associated with a fuel tank andconfigured to vent pressurized or displaced fuel vapor from the vaporspace in the fuel tank to a vapor recovery canister located outside ofthe fuel tank. The canister is designed to capture and storehydrocarbons entrained in fuel vapors that are displaced and generatedin the fuel tank during a typical vehicle refueling operation or thatare otherwise vented from the fuel tank.

The vapor recovery canister is also coupled to a vehicle engine and to apurge vacuum source. Typically, vacuum is applied to the vapor recoverycanister by the purge vacuum source whenever the vehicle engine isrunning in an effort to suck hydrocarbons captured and stored in thecanister into the engine for combustion.

In addition, valves associated with fuel tanks are sometimes providedwith vacuum-relief valves which open in response to onset of vacuumconditions in a vehicle fuel tank. When the temperature of the vehiclefuel tank drops, the fuel vapor pressure in the vehicle fuel tank candrop to a level lower than atmospheric pressure. A vacuum-relief valveis typically configured to allow air to enter the fuel tank, therebyreturning the pressure in the fuel tank to an acceptable level.

SUMMARY

A tank venting system in accordance with the present disclosure includesvapor flow controllers for regulating flow of fuel vapor between a fueltank and a fuel vapor recovery system in a vehicle. The flow of fuelvapor is controlled to maintain the pressure of fuel vapor in the fueltank at a certain pressure level or within a certain pressure range.

In illustrative embodiments, a vent apparatus includes a single-stagevalve mounted for movement in a body to regulate flow of fuel vapor froma fuel tank to a fuel vapor recovery canister along a first vapor flowpath in the body and a multi-stage valve mounted for movement in thebody to regulate flow of fuel vapor between the fuel tank and the fuelvapor recovery canister along a separate second vapor flow path in thebody. Movement of the multi-stage valve in the body is independent ofmovement of the single-stage valve in the body.

In illustrative embodiments, the multi-stage valve can be moved from aclosed position in the body to assume one of three opened positions. Afirst stage of tank venting is established upon movement of themulti-stage valve to a FIRST opened position while a second stage oftank venting is established upon movement of the multi-stage valve to aSECOND opened position. Admitting atmospheric air into the fuel tank todissipate a vacuum that has developed in the fuel tank happens uponmovement of the multi-stage valve to a THIRD opened position. Thesingle-stage valve can be moved from a closed position to an openedposition to vent pressurized fuel vapor from the fuel tank to the fuelvapor recovery canister.

In illustrative embodiments, the vent apparatus includes an electronicvalve mover that is coupled to the multi-stage valve and configured tomove the multi-stage valve to the FIRST opened position by remotecontrol. The electronic valve mover includes a stationary solenoidanchored to the body and a moveable armature mounted on a movableportion of the multi-stage valve to move therewith. When the solenoid isenergized, the movable portion of the multi-stage valve moves relativeto the body and to a relatively stationary portion of the multi-stagevalve to establish the FIRST opened position of the multi-stage valve toallow pressurized fuel vapor to flow from the fuel tank along themulti-stage vapor flow path to the fuel vapor recovery canister.

Additional features of the present disclosure will become apparent tothose skilled in the art upon consideration of the following detaileddescription of illustrative embodiments exemplifying the best mode ofcarrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 is a sectional perspective view of a tank venting systemincluding a vent apparatus in accordance with the present disclosure, afuel tank coupled to a tank passageway formed in a tank pipe included inthe vent apparatus, a fuel-vapor recovery canister coupled to a canisterpassageway formed in a canister pipe included in the vent apparatus, andshowing that the vent apparatus comprises (1) a multi-stage valveconfigured to regulate the flow of pressurized fuel vapor from the tankpassageway along a multi-stage vapor flow path into the canisterpassageway to relieve unwanted tank pressure conditions as suggested inFIGS. 5 and 7 and also to regulate the flow of outside air from thecanister passageway along the multi-stage vapor flow path into the tankpassageway to relieve unwanted tank vacuum conditions automatically assuggested in FIG. 9, (2) an electronic valve mover including a movablearmature coupled to the multi-stage valve to move therewith and asolenoid comprising a stationary coil formed to include a centralvertical channel receiving portions of the movable armature andmulti-stage valve therein, which coil can be energized by remote controlusing a valve-mover controller also included in the tank venting systemjust before a fuel tank refueling activity begins to move the armaturerelative to the coil and thus cause movement of the multi-stage valverelative to the coil to an opened tank-venting position shown in FIG. 5,and (3) a single-stage valve arranged to regulate flow of pressurizedfuel vapor from the tank passageway into the canister passageway assuggested in FIGS. 10 and 11 along a single-stage vapor flow path thatis separate from the multi-stage vapor flow path regulated by themulti-stage valve;

FIG. 2 is an exploded perspective assembly view of the componentsincluded in the vent apparatus of FIG. 1 and showing that the ventapparatus includes a monolithic base formed to include an upwardlyextending multi-stage valve housing, a tank pipe extending to the leftaway from the multi-stage valve housing, a canister pipe extending tothe right away from the multi-stage valve housing, and a downwardlyextending single-stage valve housing located below the tank pipe andcoupled to an underside of the tank pipe and an inner end of thecanister pipe, and showing that several components cooperate to form asingle-stage valve that can be mounted in the downwardly extendingsingle-stage valve housing, a portion of the upwardly extendingmulti-stage valve housing being broken away to show a fluid-flow chamberformed in a lower region of the multi-stage valve housing, an upwardlyfacing annular valve seat formed in the base and arranged to surround alarge-diameter vent aperture interconnecting the overlying fluid-flowchamber and the underlying canister passageway formed in the canisterpipe, and also showing that the vent apparatus further includes, inseries, left to right and top to bottom, a top lid sized to close a topopening formed in the multi-stage valve housing, a large-diameter O-ringlid seal, a valve-support core formed to include a downwardly openingbore sized to receive portions of the armature and the multi-stage valvetherein, a coiled return spring, a small O-ring seal, a plunger, anarmature, a coil, a spool-shaped bobbin for holding the coil, alarge-diameter sleeve for surrounding the bobbin and the coil, abobbin-support washer, an O-ring solenoid seal, a plunger-receiver cage,a diaphragm seal associated with the plunger-receiver cage and formed toinclude a small-diameter vent aperture, and a coiled cage-biasing springassociated with the upwardly facing annular valve seat formed in thebase;

FIG. 3 is a side elevation view of the vent apparatus of FIG. 1 showingeach of the multi-stage and single-stage valves in closed positions toblock fluid flow between the tank and canister passageways;

FIG. 4 is an enlarged view taken from the circled region of FIG. 3;

FIG. 5 is a view similar to FIG. 3 showing the single-stage valve in aclosed position and showing the multi-stage valve in asolenoid-activated FIRST opened position to vent pressurized fuel vaporfrom the tank passageway into the canister passageway in response toactivation of the valve-mover controller included in the tank ventingsystem to energize a coil included in the solenoid to produce a magneticfield in the armature that is coupled to the plunger in the multi-stagevalve to draw the armature further into a vertical central channelformed in the solenoid to move the plunger of the multi-stage valveupwardly from a closed position closing a small-diameter vent apertureformed in the diaphragm seal mounted on the underside of theplunger-receiver cage included in the multi-stage valve to an openedposition opening the underlying small-diameter vent aperture to allowpressurized fuel vapor to flow from the tank passageway through thesmall-diameter vent aperture into the canister passageway toward thedownstream fuel-vapor recovery canister while the diaphragm seal carriedon the plunger-receiver cage remains mated with the underlying upwardlyfacing annular valve seat formed in the base;

FIG. 6 is an enlarged view taken from the circled region of FIG. 5;

FIG. 7 is a view similar to FIGS. 3 and 5 showing the single-stage valvein a closed position and showing the multi-stage valve in apressure-activated SECOND opened position to vent pressurized fuel vaporfrom the tank passageway into the canister passageway after the pressureof that pressurized fuel vapor extant in the tank passageway has loweredfrom a first pressure (P1) suggested in FIG. 5 to a lower secondpressure (P2) suggested in FIG. 7 to allow the coiled cage-biasingspring associated with the plunger-receiver cage to act against the baseand urge the plunger-receiver cage upwardly away from an underlyingannular valve seat formed in the base of the vent apparatus to open thelarge-diameter vent aperture bounded by the upwardly facing annularvalve seat formed in the base to allow pressurized fuel vapor to flowfrom the tank passageway through the large-diameter vent aperture intothe canister passageway toward the downstream fuel-vapor recoverycanister;

FIG. 8 is an enlarged view taken from the circled region of FIG. 7;

FIG. 9 is a view similar to FIGS. 3, 5, and 7 showing the single-stagevalve in a closed position and showing the multi-stage valve in avacuum-activated THIRD opened position after vacuum (e.g., negativepressure) conditions have developed in the fuel tank to apply asufficient lifting force to a topside of a diaphragm-mount plateincluded in a lower portion of the plunger-receiver cage of themulti-stage valve to raise the plunger-receiver cage upwardly (withassistance from the coiled cage-biasing spring) to cause the underlyingdiaphragm seal to move upwardly away from the underlying annular valveseat formed in the base to open the large-diameter vent aperture definedby the annular valve seat formed in the base so that outside air atatmospheric pressure passing through the fuel-vapor recovery canistercan flow from the canister passageway through the opened large-diametervent aperture into the tank passageway to relieve unwanted vacuumconditions in the fuel tank;

FIG. 10 is a view similar to FIGS. 3, 5, 7, and 9 showing themulti-stage valve in a closed position to block flow of fuel vaporthrough the multi-stage vapor flow path and showing that pressurizedfuel vapor extant in the tank passageway acts to exert a downward forcesufficient to open the single-stage valve located in the single-stagevalve housing to allow flow of pressurized fuel vapor from the tankpassageway through the single-stage valve housing along the single-stagevapor flow path into the canister passageway without flowing through thefluid-flow chamber and the separate multi-stage vapor flow path formedin the multi-stage valve housing and either of the small-diameter andlarge-diameter vent apertures associated with the multi-stage valve;

FIG. 11 is an enlarged view taken from the circled region of FIG. 10;

FIG. 12 is a partial perspective view taken generally along lines 12-12of FIG. 11; and

FIG. 13 is a diagrammatic view of an illustrative tank venting system inaccordance with the present disclosure.

DETAILED DESCRIPTION

A tank venting system 10 is provided to control flow of air and fuelvapor between a fuel tank 12 and an emission control system including afuel vapor recovery canister 14 as suggested in FIG. 1. System 10 isused onboard a vehicle (not shown) including an engine 16 and a purgevacuum source (not shown) coupled to engine 16 and canister 14 assuggested in FIG. 3.

Tank venting system 10 also includes a vent apparatus 20 coupled to fueltank 12 via a tank conduit 13 and to fuel vapor recovery canister 14 viaa canister conduit 15 as suggested in FIG. 1. Vent apparatus 20 includesa single-stage valve 21 and a separate multi-stage valve 22.Single-stage valve 21 is used to regulate flow of pressurized fuel vaporfrom fuel tank 12 to fuel vapor recovery canister 14 as suggested, forexample, in FIG. 10. Multi-stage valve 22 is used to regulate flow ofair and fuel vapor between fuel tank 12 and fuel vapor recovery canister14 as suggested, for example, in FIGS. 5, 7, and 9.

Vent apparatus 20 also includes an electronic valve mover 24 associatedwith multi-stage valve 22 and configured to move portions of multi-stagevalve by remote control to vent pressurized fuel vapor from fuel tank 12to fuel vapor recovery canister 14 on demand Electronic valve mover 24includes an armature 26 that is mounted on multi-stage valve 22 to movetherewith and a stationary solenoid 28 comprising a coil 280 that can beenergized using electricity to produce a magnetic field in armature 26that causes armature 26 to move relative to solenoid 28. Such movementof armature 26 causes multi-stage valve 22 to move relative to thestationary solenoid 28 from a closed position shown in FIG. 3 to a FIRSTopened position shown in FIG. 5 to allow pressurized fuel vapor to flowfrom fuel tank 12 to fuel vapor recovery canister 14. A valve-movercontroller 18 is also included in tank venting system 10 and is operableto activate valve mover 24 to move multi-stage valve 22 to the FIRSTopened position to vent pressurized fuel vapor from fuel tank 12 to fuelvapor recovery canister 14 as suggested in FIG. 5.

Fuel vapor recovery canister 14 is used to capture and storehydrocarbons entrained in fuel vapor discharged from fuel tank 12 byvent apparatus 20. Canister 14 may be a carbon canister or othersuitable fuel vapor treatment device. Canister 14 is exposed to outsideatmospheric air 11 as suggested in FIG. 3. A canister vent solenoidvalve 14V is coupled to fuel vapor recovery canister 14 to regulatefluid communication between canister 14 and the atmosphere 11 inillustrative embodiments of the present disclosure as suggested in FIG.13. It is within the scope of the present disclosure to place a pressuresensor 15 in canister conduit 15 as suggested in FIG. 13.

A base 30 included in vent apparatus 20 is formed to include passagewaysand chambers that function to conduct fluid between the tank conduit 13that is coupled to fuel tank 12 and the canister conduct 15 that iscoupled to fuel vapor recovery canister 14. Base 30 is formed to includeone holding compartment 30H1 for holding the single-stage valve 21 andanother holding compartment 30H2 for holding the multi-stage valve 22and the solenoid 28 as suggested in FIG. 1. Base 30 is formed to includevent apertures 331, 332, 351, and 352 linking those compartments 30H1,30H2 with the tank conduit 13 associated with fuel tank 12 and thecanister conduit 15 associated with canister 14 as suggested in FIGS. 5,7, 9, and 10. Base 30 is a monolithic component made of a plasticmaterial in illustrative embodiments of the present disclosure.

Base 30 also includes a single-stage valve housing 31 for single-stagevalve 21 and a multi-stage valve housing 32 for multi-stage valve 22 assuggested in FIG. 1. Single-stage valve housing 31 is formed to includefirst holding compartment 30H1 as suggested in FIG. 1. Multi-stage valvehousing 32 is formed to include second holding compartment 30H2 assuggested in FIG. 1.

Base 30 includes a tank pipe 33 coupled to tank conduit 13 and acanister pipe 35 coupled to canister conduit 15 as suggested in FIG. 1.Tank pipe 33 is formed to include a tank passageway 33P that is in fluidcommunication with tank conduit 13 and each of holding compartments30H1, 30H2 as suggested in FIG. 1. Canister pipe 35 is formed to includea canister passageway 35P that is in fluid communication with each ofholding compartments 30H1, 30H2 and canister conduit 15 as suggested inFIGS. 1 and 10.

Multi-stage valve 22 regulates fluid flow in base 30 between the tankand canister conduits 13, 15 through the second holding compartment 30H2formed in multi-stage valve housing 32 as suggested in FIGS. 3, 5, 7, 9,and 10. Multi-stage valve 22 can be moved relative to the base 30 from aclosed position shown in FIG. 3 to either: (1) a solenoid-activatedFIRST opened position shown in FIG. 5 to vent pressurized fuel vaporfrom fuel tank 12 through a fluid-flow chamber 32C defined by holdingcompartment 30H2 along a multi-stage vapor flow path to fuel vaporrecovery canister 14 to pre-vent pressurized fuel vapor in the fuel tank12 before initiation of a fuel tank refueling activity, (2) apressure-activated SECOND opened position shown in FIG. 7 to ventpressurized fuel vapor from fuel tank 12 through fluid-flow chamber 32Calong the multi-stage vapor flow path to fuel vapor recovery canister 14when pressure of fuel vapor in fuel tank exceeds a predeterminedpressure level, or (3) a vacuum-activated THIRD opened position shown inFIG. 9 to admit outside air 11 passing through fuel vapor recoverycanister 14 through fluid-flow chamber 32C along the multi-stage vaporflow path into fuel tank 12 to relieve vacuum conditions in fuel tank12.

Single-stage valve 21 regulates fluid flow in base 30 between the tankand canister conduits 13, 15 through the first holding compartment 30H1formed in single-stage valve housing 31 as suggested in FIGS. 3, 5, and7. Single-stage valve 21 can be moved relative to the base 30 byhigh-pressure fuel vapor extant in tank passageway 33P of tank pipe 33from a closed position shown in FIGS. 1 and 3 to a pressure-activatedopened position shown in FIG. 10 to vent pressurized fuel vapor fromfuel tank 12 through a fluid-flow chamber 31C defined by holdingcompartment 30H1 along a single-stage vapor flow path to fuel vaporrecovery canister 14.

Holding compartment 30H1 formed in single-stage valve housing 31 issized and shaped to contain the single-stage valve 21 as suggested inFIG. 1. This compartment 30H1 provides a first fluid-flow chamber 31Cthrough which fluid (e.g. fuel vapor or air) can flow as it travelsbetween fuel tank 12 and fuel vapor recovery canister 14, for example,to vent high pressure fuel vapor from fuel tank 12 to fuel vapor recovercanister 14 when single-stage valve 21 is opened as suggested in FIGS.10-12. Holding compartment 30H2 formed in multi-stage valve housing 32is sized and shaped to contain valve mover 24 (e.g., armature 26 andsolenoid 28) and multi-stage valve 22 as suggested in FIG. 1. Holdingcompartment 30H2 provides an upper solenoid-storage chamber containingsolenoid 28 and upper portions of armature 26 and multi-stage valve 22as also suggested in FIG. 1. Holding compartment 30H2 also providessecond fluid-flow chamber 32C below upper solenoid-storage chamber 132Cto link tank passageway 33P of tank pipe 33 in fluid communication withcanister passageway 35P of canister pipe 35 as suggested in FIG. 1.Fluid (e.g. fuel vapor) can flow through a second fluid-flow chamber 32Calong the multi-stage vapor flow path as it travels between fuel tank 12and fuel vapor recovery canister 14, for example, before initiation of atank-refueling activity, or a tank-pressuring activity to alleviateunwanted tank vacuum conditions.

Base 30 includes a tank pipe 33 coupled to fuel tank 12 via tank conduit13 and a canister pipe 35 coupled to fuel vapor recovery canister 14 viacanister conduit 15 as suggested in FIG. 1. Tank pipe 33 has an inlet330 opening into tank conduit 13, a first outlet 331 opening into afluid-flow chamber 31C formed in the holding compartment 30H1 formed insingle-stage valve housing 31, and a second outlet 332 opening into asecond fluid-flow chamber 32C provided in the holding compartment 30H2formed in multi-stage valve housing 32 as suggested in FIG. 1. Canisterpipe 35 has a first inlet 351 opening into the first fluid-flow chamber31C provided in compartment 30H1 formed in single-stage valve housing31, a second inlet 352 opening into the second fluid-flow chamber 32Cprovided in lower compartment 30H2 formed in multi-stage valve housing32, and an outlet 350 opening into canister conduit 15 as suggested inFIG. 1. When multi-stage valve 22 is opened as suggested in FIGS. 5, 7,and 9, fluid (e.g. fuel vapor and air) can flow between tank andcanister pipes 33, 35 through second fluid-flow chamber 32C provided inmulti-stage valve housing 32 along the multi-stage vapor flow pathwithout flowing through the first fluid-flow chamber 31C provided insingle-stage valve housing 31 along the single-stage vapor flow path.When single-stage valve 21 is opened as suggested in FIG. 10, fluid(e.g. pressurized fuel vapor) can flow between tank and canister pipes33, 35 through first fluid-flow chamber 31C along the single-stage vaporflow path without flowing through second fluid-flow chamber 32C alongthe multi-stage vapor flow path.

Vent apparatus 20 comprises a multi-stage valve 22, an electronic valvemover 24 associated with multi-stage valve 22, and a single-stage valve21 as suggested in FIGS. 1 and 2. Multi-stage valve 22 is configured toregulate the flow of pressurized fuel vapor from the tank passageway 33Pinto the canister passageway 35P to relieve unwanted tank pressureconditions as suggested in FIGS. 5 and 7 and also to regulate the flowof outside air from the canister passageway 35P into the tank passageway33P to relieve unwanted tank vacuum conditions automatically assuggested in FIG. 9. Valve mover 24 includes a movable armature 26coupled to multi-stage valve 22 to move therewith and a solenoid 28comprising a stationary coil 280 formed to include a central verticalchannel 280C receiving portions of the movable armature 26 andmulti-stage valve 22 therein as suggested in FIGS. 1 and 2. Coil 280 canbe energized by remote control using a valve-mover controller 18 alsoincluded in tank venting system 10 for example, just before initiationof a tank-refueling activity for fuel tank 12 to move armature 26relative to coil 280 and thus cause movement of multi-stage valve 22relative to coil 280 to tank-venting FIRST opened position shown in FIG.5. Single-stage valve 21 is arranged to regulate flow of pressurizedfuel vapor from the tank passageway into the canister passageway assuggested in FIGS. 10 and 11 along a single-stage vapor flow path thatis separate from the multi-stage vapor flow path regulated bymulti-stage valve 22.

An exploded perspective assembly view of the components included in ventapparatus 20 is provided in FIG. 2. Vent apparatus 20 includes amonolithic base 30 formed to include an upwardly extending multi-stagevalve housing 32, a tank pipe 33 extending to the left away frommulti-stage valve housing 32, a canister pipe 35 extending to the rightaway from multi-stage valve housing 32, and a downwardly extendingsingle-stage valve housing 31 located below tank pipe 33 and coupled toan underside of tank pipe 33 and an inner end of canister pipe 35.

Several components included in vent apparatus 20 cooperate to form asingle-stage valve 21 that can be mounted in the downwardly extendingsingle-stage valve housing 31 as suggested in FIGS. 1 and 2.Single-stage valve 21 comprises a relief valve gasket seal 211, abacking plate 212 that cooperates with gasket seal 211 to form a closure210, a closure-biasing return spring 213, and a relief valve cover 214.Closure 210 is movable in fluid-flow chamber 31C against a closing forcegenerated by return spring 213 between a closed position (see FIGS. 1and 3) engaging an annular valve seat 31S included in body 30 andarranged to surround the first outlet 331 that couples tank passageway33P and fluid-flow chamber 31C in fluid communication and an openedposition (see FIG. 10) disengaging annular valve seat 31S in response toan opening force exerted on a topside of closure 210 by pressurized fuelvapor in excess of a predetermined level in tank passageway 33P of tankpipe 33.

Multi-stage valve 22 is separated fluidly from single-stage valve 21 assuggested in FIG. 1 because multi-stage valve 22 is associated with asecond outlet 332 of tank pipe 33 while single-stage valve 21 isassociated with a separate first outlet 331 of tank 33. A portion of theupwardly extending multi-stage valve housing 22 is broken away in FIG. 2to show a fluid-flow chamber 32C formed in a lower region of themulti-stage valve housing 32 and an upwardly facing annular valve seat32S formed in base 30 and arranged to surround a large-diameter ventaperture defined by second inlet 352 of canister pipe 35 and arranged tointerconnect the overlying fluid-flow chamber 32C and the underlyingcanister passageway 35P formed in canister pipe 35.

Vent apparatus 20 further includes as suggested in FIG. 2, in series,left to right and top to bottom, a top lid 201 sized to close a topopening 32T formed in multi-stage valve housing 32, a large-diameterO-ring lid seal 202, a valve-support core 203 formed to include adownwardly opening bore 203B sized to receive portions of armature 26and multi-stage valve 22 therein, a coiled return spring 221, a smallO-ring seal 222, a plunger 223, an armature 26, a coil 280, aspool-shaped bobbin 281 for holding coil 280, a large-diameter sleeve282 for surrounding the bobbin 281 and the coil 280, a bobbin-supportwasher 283, an O-ring solenoid seal 204, a plunger-receiver cage 224, adiaphragm seal 225 associated with the plunger-receiver cage 224 andformed to include a small-diameter vent aperture 226, and a coiledcage-biasing spring 227 associated with the upwardly facing annularvalve seat 32S formed in base 30.

Each of the multi-stage and single-stage valves 22, 21 is shown in FIG.3 in closed positions to block fluid flow between the tank and canisterpassageways 33P, 35P. These valves 22, 21 can be opened at various timesand under various tank-pressure conditions as described and shown hereinto allow fluid flow between the tank and canister passageways 33P, 35P.

A solenoid-activated first-stage venting of pressurized fuel vapor fromthe tank passageway 33P into the canister passageway 35P takes place inaccordance with the present disclosure following movement of multi-stagevalve 22 to a FIRST opened position in response to activation ofvalve-mover controller 18 included in tank venting system 10 to energizea coil 280 included in solenoid 28 to produce a magnetic field inarmature 26 that is coupled to plunger 223 in the multi-stage valve 22to draw armature 26 further into a vertical central channel 280C formedin the solenoid 28 to move plunger 223 of multi-stage valve 22 upwardlyfrom a closed position closing a small-diameter vent aperture 226 formedin the diaphragm seal 225 mounted on the underside of theplunger-receiver cage 224 included in the multi-stage valve 22 to anopened position opening the underlying small-diameter vent aperture 226to allow pressurized fuel vapor to flow from the tank passageway 33Pthrough the small-diameter vent aperture 226 into the canisterpassageway 35P toward the downstream fuel-vapor recovery canister 14while the diaphragm seal 225 carried on the plunger-receiver cage 226remains mated with the underlying upwardly facing annular valve seat 32Sformed in the base 30.

A subsequent second-stage venting of pressurized fuel vapor from thetank passageway 33P into the canister passageway 35P takes place inaccordance with the present disclosure following movement of multi-stagevalve 22 to a THIRD opened position after the pressure of thatpressurized fuel vapor extant in the tank passageway 33P has loweredfrom a first pressure (P1) suggested in FIG. 5 to a lower secondpressure (P2) suggested in FIG. 7 to allow the coiled cage-biasingspring 227 associated with the plunger-receiver cage 224 to act againstthe base 30 and urge the plunger-receiver cage 224 upwardly away from anunderlying annular valve seat 35S formed in the base 30 of the ventapparatus 20 to open the large-diameter vent aperture 352 bounded by theupwardly facing annular valve seat 32S formed in the base 30 to allowpressurized fuel vapor to flow from the tank passageway 33P through thelarge-diameter vent aperture 352 into the canister passageway 35P towardthe downstream fuel-vapor recovery canister 14.

Multi-stage valve 22 is moved to a SECOND opened position in accordancewith the present disclosure when an unwanted vacuum is created in fueltank 12. Vacuum (e.g., negative pressure) conditions developed in thefuel tank 12 as suggested in FIG. 9 cause a sufficient lifting force (F)to be applied to a topside of a diaphragm-mount plate 224P included in alower portion of plunger-receiver cage 224 of multi-stage valve 22 toraise plunger-receiver cage 224 upwardly (with assistance from thecoiled cage-biasing spring 227) to cause the underlying diaphragm seal225 to move upwardly away from the underlying annular valve seat 32Sformed in the base 30 to open the large-diameter vent aperture 352defined by the annular valve seat 32S formed in the base 30 so thatoutside air at atmospheric pressure passing through the fuel-vaporrecovery canister 14 can flow from the canister passageway 35P throughthe opened large-diameter vent aperture 352 into the tank passageway 33Pto relieve unwanted vacuum conditions in the fuel tank 12.

Multi-stage valve 22 is shown in a closed position in FIG. 10.Pressurized fuel vapor extant in the tank passageway 33P acts to exert adownward force sufficient to open the single-stage valve 21 located inthe single-stage valve housing 31 to allow flow of pressurized fuelvapor from the tank passageway 33P through the single-stage valvehousing 31 into the canister passageway 35P without flowing through thefluid-flow chamber 32C formed in the multi-stage valve housing 22 andeither of the small-diameter and large-diameter vent apertures 226, 352associated with the multi-stage valve 22.

Tank venting system 10 comprises a base 30, a single-stage valve 21, anda multi-stage valve 22 as suggested in FIGS. 1 and 2. Base 30 is formedto include a tank passageway 33P adapted to be coupled in fluidcommunication to a fuel tank 12, a canister passageway 35P adapted to becoupled in fluid communication to a fuel vapor recovery canister 14, afirst fluid-flow chamber 31C arranged to interconnect the tank andcanister passageways 33P, 35P in fluid communication, and a separatesecond fluid-flow chamber 32C arranged to interconnect the tank andcanister passageways 33P, 35P in fluid communication as suggested inFIG. 1. The single-stage valve 21 is arranged to regulate flow of fuelvapor between the tank and canister passageways 33P, 35P through thefirst fluid-flow chamber 31C. The multi-stage valve 22 is arranged toregulate flow of fuel vapor between the tank and canister passageways33P, 35P through the second fluid-flow chamber 32C. Movement ofmulti-stage valve 22 relative to body 30 is independent of movement ofsingle-stage valve 21 relative to body 30.

Tank venting system 10 further comprises an electronic valve mover 24coupled to multi-stage valve 22 and configured to move multi-stage valve22 from a closed position shown in FIG. 3 to a FIRST opened positionshown in FIG. 5 by remote control to allow pressurized fuel vapor toflow from fuel tank 12 through second fluid-flow chamber 32C to fuelvapor recovery canister 14. Multi-stage valve 22 is moved from the FIRSTopened position to a SECOND opened position different than the FIRSTopened position to allow pressurized fuel vapor to flow from fuel tank12 through second fluid-flow chamber 32C to fuel vapor recovery canister14 as suggested in FIG. 7. Multi-stage valve 22 is configured to movefrom a closed position to a THIRD opened position different from theFIRST opened position to admit fuel vapor that has exited the fuel vaporrecovery canister 14 and passed through second fluid-flow chamber 32Cinto fuel tank 12 to dissipate a vacuum that has developed in fuel tank12 as suggested in FIG. 9.

Body 30 further includes a tank pipe 33 formed to include the tankpassageway 33P as suggested in FIG. 1. Tank pipe 33 includes an innerend, an outer end, and a side wall arranged to extend between the innerand outer ends and formed to include a first outlet 331 opening into thefirst fluid-flow chamber 32C. The inner end of tank pipe 33 is formed toinclude a second outlet 332 opening into the second fluid-flow chamber32C. The outer end of tank pipe 33 is formed to include an inlet 330communicating with fuel tank 14.

Body 30 also includes a canister pipe 35 formed to include the canisterpassageway 35P as suggested in FIG. 1. Canister pipe 35 includes aninner end, an outer end, and a side wall arranged to extend between theinner and outer ends and formed to include a second inlet 352 openinginto the second fluid-flow chamber 32C. The inner end of the canisterpipe 35 is formed to include a first inlet 351 opening into the firstfluid-flow chamber 31C. The outer end of canister pipe 35 is formed toinclude an outlet 350 communicating with fuel vapor recovery canister14.

One purpose of vent apparatus 20 is to contain evaporative emissionswithin fuel tank 12 by isolating fuel tank 12 from canister 14 undermost conditions and closing tank venting system 10. During vehicledriving conditions, vent apparatus 20 will be signaled to open so thattank venting system 10 can draw fuel from fuel tank 12 as needed forrunning vehicle engine 16 and thus draw the fuel vapors that are in thefuel vapor recovery canister 14 back to the fuel tank 12. The fuel vaporrecovery canister 14 then draws in filtered fresh air from theatmosphere 11.

In a hybrid vehicle having an engine that is not running or in a vehiclehaving a canister that have very low purging, then vent apparatus 20will remain closed to keep the tank venting system 10 closed. This willagain keep the fuel vapors contained in the fuel tank 12 and will allowmore efficient purging of fuel vapor recovery canister vapors withoutdrawing fuel vapors from the fuel tank 12.

When the vehicle operator prepares to fill the fuel tank 12, there is abutton (i.e., valve-mover controller 18) that they must first push toactivate the vent apparatus 20 to open, relieving any vacuum or pressurethat may have built up in the fuel tank 12. That tank vacuum or pressureis always directed through the vent apparatus 20 and the fuel vaporrecovery canister 14. Under any circumstance when the pressure or vacuumin the fuel tank 12 exceeds the required application limits, a signaltells the vent apparatus 20 to activate and open to relieve thatpressure or vacuum via the fuel vapor recovery canister 14. Themechanical relief valves are available in the event the coil or mainshutoff valve fail for any reason, or do not respond as expected tothose pressure or vacuum excesses.

The coil 280 is designed to be enclosed in a housing that has a cap 201that contains terminals with a treacherous path to reduce moistureingress. Other designs have terminations that are short and straightinto the coil winding area and are thought to provide a leak path formoisture ingress. The cap 201 is sealed by an O-ring 202 and can beremoved for inspection and serviceability of the coil assembly withoutsacrificing the complete valve.

The single-stage valve 21 is located on the tank port side as suggestedin FIG. 1 to make the opening a direct process with a reduction ofcomponents as compared to other designs. A wall portion 215 is providedin the pressure relief cavity 31C that allows for a smoothing effect onthe air flow so that the pressure-relief seal 211 pushes away from theseat 31S in a straight fashion without tilting in the cavity 31C. Thatwall portion 215 is shown, for example, in FIG. 11.

By lengthening the core and shortening the armature 26 the method ofsnap-on attachment of the armature 26 to the plunger 223 is also simplerthan other designs. The small O-ring 222 that is placed on theplunger/armature assembly 223, 26 is for noise reduction when thearmature 26 closes to the core. The method is simpler than otherdesigns.

The invention claimed is:
 1. A tank venting system comprising a base formed to include a tank passageway adapted to be coupled in fluid communication to a fuel tank, a canister passageway adapted to be coupled in fluid communication to a fuel vapor recovery canister, a first fluid-flow chamber arranged to interconnect the tank and canister passageways in fluid communication, and a separate second fluid-flow chamber arranged to interconnect the tank and canister passageways in fluid communication, a single-stage valve arranged to regulate flow of fuel vapor between the tank and canister passageways through the first fluid-flow chamber, and a multi-stage valve arranged to regulate flow of fuel vapor between the tank and canister passageways through the second fluid-flow chamber, wherein the multi-stage valve comprises a coiled return spring, a small O-ring seal, a plunger, a plunger-receiver cage, a diaphragm seal associated with the plunger-receiver cage and formed to include a small-diameter vent aperture, and a coiled cage-biasing spring associated with an upwardly facing annular valve seat formed in the base.
 2. The tank venting system of claim 1, wherein movement of the multi-stage valve relative to the base is independent of movement of the single-stage valve relative to the base.
 3. The tank venting system of claim 1, further comprising an electronic valve mover coupled to the multi-stage valve and configured to move the multi-stage valve from a closed position to a first opened position by remote control to allow pressurized fuel vapor to flow from the fuel tank through the second fluid-flow chamber to the fuel vapor recovery canister.
 4. The tank venting system of claim 3 wherein the multi-stage valve is moved from the first opened position to a second opened position different than the first opened position to allow pressurized fuel vapor to flow from the fuel tank through the second fluid flow chamber to the fuel vapor recovery canister.
 5. The tank venting system of claim 4, wherein the multi-stage valve is configured to move from a closed position to a third opened position different from the first position to admit fuel vapor that has exited the fuel vapor recover canister and passed through the second fluid-flow chamber into the fuel tank to dissipate a vacuum that has developed in the fuel tank.
 6. The tank venting system of claim 1, wherein the base includes a tank pipe formed to include the tank passageway, the tank pipe includes an inner end, and outer end, and a side wall arranged to extend between the inner and outer ends and formed to include a first outlet opening into the first fluid-flow chamber, and the inner end of the tank pipe is formed to include a second outlet opening into the second fluid-flow chamber and an outer end of the tank pipe is formed to include an inlet communicating with the fuel tank.
 7. The tank venting system of claim 6, wherein the base includes a canister pipe formed to include the canister passageway, the canister pipe includes an inner end, and outer end, and a side wall arranged to extend between the inner and outer ends and formed to include a second inlet opening into the second fluid-flow chamber, the inner end of the canister pipe is formed to include a first end opening into the first fluid-flow chamber, and the outer end of the canister pipe is formed to include an outlet communicating with the fuel vapor recovery canister.
 8. The tank venting system of claim 1, wherein the body base includes a canister pipe formed to include the canister passageway, the canister pipe includes an inner end, and outer end, and a side wall arranged to extend between the inner and outer ends and formed to include a second inlet opening into the second fluid-flow chamber, the inner end of the canister pipe is formed to include a first end opening into the first fluid-flow chamber, and the outer end of the canister pipe is formed to include an outlet communicating with the fuel vapor recovery canister.
 9. The tank venting system of claim 1, wherein the canister passageway has a first vent aperture from the first fluid-flow chamber and the canister passageway has a second vent aperture from the second fluid-flow chamber.
 10. The tank venting system of claim 1, wherein the second fluid-flow chamber is adapted for receiving fuel vapor flow directly from the canister passageway and enabling flow directly into the tank passageway while bypassing the first fluid-flow chamber.
 11. The tank venting system of claim 1, wherein the single-stage valve is adapted to enable flow of fuel vapor from the tank passageway into the canister passageway without the fuel vapor flowing into the second fluid-flow chamber. 